One type of prior art flip chip light emitting diode (FCLED) die 10 is shown in FIGS. 1A-1B. As shown in FIG. 1B, during fabrication the flip chip light emitting diode (FCLED) die 10 includes a substrate 12, and an epitaxial stack 14 on the substrate 12. The epitaxial stack 14 includes an n-type confinement layer 16, a multiple quantum well (MQW) layer 18 in electrical contact with the n-type confinement layer 16 configured to emit electromagnetic radiation, and a p-type confinement layer 20 in electrical contact with the multiple quantum well (MQW) layer 18. The flip chip light emitting diode (FCLED) die 10 also includes a mirror layer 22, a p-metal layer 24 in electrical communication with the p-type confinement layer 20, and a p-pad 28 in electrical communication with the p-type confinement layer 20 via the p-metal layer 24.
In addition, the flip chip light emitting diode (FCLED) die 10 includes an electrical isolator layer 26 configured to electrically isolate the p-pad 28 and the p-metal layer 24. The flip chip light emitting diode (FCLED) die 10 also includes a plurality of n-pads 30 in electrical contact with the n-type confinement layer 16. As shown in FIG. 1A, the p-pad 28 extends along one side edge of the flip chip light emitting diode (FCLED) die 10, and the n-pads 30 extend generally parallel to the p-pad 28. As shown in FIG. 2, during a packaging process, the flip chip light emitting diode (FCLED) die 10 can be flip chip mounted to a module substrate 32 with the p-pad 28 bonded to a p-electrode 34 on the module substrate 32, and with the n-pads 30 bonded to n-electrodes 36 on the module substrate 32.
One characteristic of the flip chip light emitting diode (FCLED) die 10 is that the p-pad 28 and the n-pads 30 are separated by a gap WG. The size of the gap WG affects the output radiation of the flip chip light emitting diode (FCLED) die 10, particularly along the outside edge of the p-pad 28. For example, if the gap WG is relatively large, then the distance between the p-pad 28 and the n-pads 30 would also be large, and the output radiation along the outside edge of the p-pad 28 would be low. The width WP of the p-pad 28 is also dependent on the size of the gap WG, such that a smaller width WP can present problems during a subsequent packaging process.
Another characteristic of the flip chip light emitting diode (FCLED) die 10 is that WG cannot be made so small that electrical shorting can occur between the p-pad 28 and the n-pad 30. These conflicting characteristics present a dilemma for achieving the optimal sizes for the gap width WG, the width WP of the p-pad 28, and the width WN of the n-pads 30. The present disclosure provides a solution for solving this dilemma and for improving the output radiation of a flip chip light emitting diode (FCLED) die. In addition, the present disclosure provides a method for fabricating flip chip light emitting diode (FCLED) dice that does not require additional masks, and does not adversely affect current process windows.
However, the foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings. Similarly, the following embodiments and aspects thereof are described and illustrated in conjunction with a flip chip light emitting diode (FCLED) die which are meant to be exemplary and illustrative, not limiting in scope.